1. Technical Field
The present disclosure relates to a bonding structure, and more particularly, relates to a bonding structure using an anisotropic conductive film.
2. Description Of the Related Art
In the rapidly changing information age, electronic products have become closely related to our life and work. As the electronic products are becoming thinner, smaller, lighter, and more precise, in order to solve problems relating to incapability of high-temperature tin-lead welding in circuits such as flexible printed circuit (FPC), integrated circuit (IC), liquid crystal display (LCD), touch panel, and like products' circuits or pin connections, an anisotropic conductive film (hereafter referred to as ACF) and a related circuit connection method thereof have been developed for solving all kinds of circuit connection problems of electronic products.
ACF referred in this text is meant to include the anisotropic conductive film which is made into a form of film and an anisotropic conductive adhesive (ACA) which is made into a form of adhesive. ACF is made by disposing a plurality of conductive particles inside a semi-solid resin or by mixing a plurality of conductive particles with a strong adhesive, wherein the ACF has a characteristic of vertically conducting and horizontally non-conducting. While bonding, the anisotropic conductive film can be laid between the components to be bonded. After heating and pressurizing, ACF connects the components to be bonded by effects of temperature and pressure, so as to make the bonded components have conductive effect in a vertical direction and no conductive effect in a horizontal direction.
FIG. 1 illustrates conventional bonding structure of two components by ACF. FIG. 1 is drawn with an assumption of every component being transparent so as to make it convenient for viewing. As shown in FIG. 1, a plurality of bonding pads 4 are disposed on a substrate 2, wherein each of the bonding pads 4 is connected with a conducting wire 6; a plurality of bonding pads 10 are disposed on a substrate 8, wherein each of the bonding pads 10 is connected with a conducting wire 12; and an ACF layer 14 is laminated between the bonding pads 4 and the bonding pads 10 to form a bonding region 16 and a peripheral region 18. The bonding region 16 is an overlapping bonding region of the bonding pads 4 and the bonding pads 10, and the peripheral region 18 is a region located in the periphery of the bonding region 16. As there exists a relatively smaller space between the left-and-right adjacent bonding pads, while bonding, a plurality of conductive particles is easily extruded into the peripheral region 18 by pressure effect such that short circuit occurs between the left-and-right adjacent bonding pads. For example, of bonding, the conductive particles 20 in the ACF layer 14 may be extruded or over flown (can generally refer to floating) into the peripheral region 18 to gather and locate between two adjacent left-and-right bonding pads 4 and/or two adjacent left-and-right bonding pads 10, easily leading to short circuit.
Consequently, a novel bonding structure is still required for avoiding the above short circuit problem.